The present invention relates to an array of tools which can be used in combination to produce automatically a variety of patterns of operation. Such an array may be used, for example, in silviculture, with each tool of the array either preparing a region of ground to receive a tree, or planting a tree in a region which has already been prepared, with the overall action of the array arranged to provide a required density and pattern of plants.
The applicant's earlier U.S. Pat. No. US-A-4790400 describes and claims a vehicle suitable for use in silviculture which can be arranged to carry an array of planting tools which may operate simultaneously. The vehicle and the tool array may be controlled by an operator in a cab mounted centrally on the vehicle. Such a vehicle can operate on very difficult ground and, with appropriate tools, can maintain high planting rates and desired work quality.
A number of problems are encountered in using an array of tools which operate simultaneously. A prime requirement, particularly in silviculture but also in other types of cultivation, is the achievement of an optimum planting density. It is of course possible to set spacing between the tools in the array so as to give the required density. In practice however it is found that if predetermined relative positions are used for the tools then a significant proportion of the tools will then be located over regions of ground which are unsuitable for planting. This problem can be overcome by manual adjustment of the position of the tools. However such manual adjustment adds significantly to the time taken for the planting process making it difficult to achieve high enough planting rates.